Day 3 of Seahawks training camp meant the first day of practicing in pads, so it was a little bit louder at the VMAC on Sunday.

Marcus Trufant has played his final snap for the Seahawks this season.

The veteran cornerback was placed on injured reserve on Monday because of a back situation that prevented Trufant from playing in the team’s pre-bye week game against the New York Giants.

“We’re just really disappointed for him,” coach Pete Carroll said after practice. “Just a beautiful kid in the program and the community and all that. He’ll miss the season, which means so much to him and all of us.”

Carroll originally called Trufant’s injury a bruised sacrum and said it was not related to the disc problem that forced him to miss the first six games of the 2009 season. But additional tests showed that the latest injury is related to the previous one.

“This is a reoccurring back situation,” Carroll said. “We didn’t realize it really is what happened before. So we’ve got to take care of him and he’ll be out for quite some time. He’s very uncomfortable and it hasn’t been easy for him.”

Carroll said they will try to avoid surgery on Trufant’s back, as was the case in 2009.

“At this point, just waiting,” Carroll said. “They’re going to wait and see him through and try to get him well and get him comfortable.”

Trufant, who played at Tacoma’s Wilson High School and Washington State University, was not available for comment.

But his absence speaks volumes, not just for the defense but the entire team. Trufant was voted the defensive captain by his teammates this season and was by far the most experienced of the team’s defensive backs, having started 123 games since the Seahawks made him the 11th pick overall in the 2003 NFL Draft.

“It’s very unfortunate, because he was a big part of the team,” said second-year cornerback Walter Thurmond, who will replace Trufant on the left side – as he did on the 36-25 victory over the Giants.

“A lot of the DBs, especially all the young guys, really looked up to him. So hopefully he’s still around so he can keep giving us knowledge.”

Thurmond will make his fourth NFL start at cornerback on Sunday, when the Seahawks play the Browns in Cleveland. On the right side is cornerback Brandon Browner, who will make his sixth NFL start after playing the CFL the past four seasons. The safeties are Earl Thomas, a first-round draft choice last year who has started 21 games; and Kam Chancellor, a fifth-round pick last year who will make his sixth start against the Browns.

How ready is Thurmond for this opportunity? “I’ve been ready since I came into camp,” Thurmond said.

Then, however, it was thought that Thurmond would be the starter opposite Trufant. That was before Thurmond sprained an ankle and Browner pushed his way – literally – into the starting lineup with his physical style.

Now, both will start – as they did against the Giants, when Browner returned an interception a club-record 94 yards for the touchdown to ice the victory and Thurmond made a couple of key plays in coverage to help the Seahawks rally to the win.

“I got comfortable out there,” Thurmond said. “I was able to get my feet wet and was able to make plays out there. I just have to continue that through the rest of the season.”

Trufant played in the Oct. 2 game against the Atlanta Falcons, but his back started bothering him the following Wednesday. But Sunday, he could not tie his shoes, let alone play against the Giants.

The Seahawks envisioned Thurmond developing into a starter when they selected him in the fourth round of last year’s draft. That time has come.

“Walter will jump in right now and assume the starting role, and we’ll expect him to play like Tru and live up to it,” Carroll said. “Walter expects nothing less than that.”